2003 GMC SIERRA DENALI Owners Manual

6. Then replace the
pressure cap. Be sure
the pressure cap is
hand-tight and
fully seated. Engine Fan Noise
Your vehicle has a clutched engine cooling fan. When the
clutch is engaged, the fan spins faster to provide more air
to cool the engine. In most everyday driving conditions,
the fan is spinning slower and the clutch is not fully
engaged. This improves fuel economy and reduces fan
noise. Under heavy vehicle loading, trailer towing and/or
high outside temperatures, the fan speed increases as
the clutch more fully engages.
So you may hear an
increase in fan noise. This is normal and should not be
mistaken as the transmission slipping or making extra
shifts. It
is merely the cooling system functioning properly.
The fan will slow down when additional cooling is not
required and the clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch partially
disengages.
5-36

Power Steering Fluid
When to Check Power Steering Fluid
It is not necessary to regularly check power steering fluid
unless you suspect there is a leak in the system or
you hear an unusual noise. A fluid loss in this system
could indicate a problem. Have the system inspected
and repaired. See
Engine Compartment Overview
on page
5-12 for reservoir location.
How to Check Power Steering Fluid
Turn the key off, let the engine compartment cool down,
wipe the cap and the top of the reservoir clean, then
unscrew the cap and wipe the dipstick with a clean rag.
Replace the cap and completely tighten it. Then remove
the cap again and look at the fluid level on the dipstick.
The level should be at the
FULL COLD mark.
If necessary, add only enough fluid to bring the
level up to the mark.
What to Use
To determine what kind of fluid to use, see Part Dr
Recommended Fluids and Lubricants on page 6- 16.
Always use the proper fluid. Failure to use the proper
fluid can cause leaks and damage hoses and seals.
5-37

Windshield Washer Fluid
What to Use
When you need windshield washer fluid, be sure to read
the manufacturer’s instructions before use. If you will
be operating your vehicle in an area where the
temperature may fall below freezing, use a fluid that
has sufficient protection against freezing. See
Engine
Compartment Overview
on page 5-12 for reservoir
location.
Adding Washer Fluid
Open the cap with the
washer symbol on it.
Add washer fluid until
the tank is full.
Notice:
When using concentrated washer fluid, follow
the manufacturer’s instructions for adding water.
Don’t
mix water with ready-to-use washer fluid.
Water can cause the solution to freeze and
damage your washer fluid tank and other parts
of the washer system.
Also, water doesn’t
clean as well
as washer fluid.
Fill your washer fluid tank only three-quarters
full when
it’s very cold. This allows for
expansion if freezing occurs, which could damage the tank
if it is completely full.
Don’t use engine coolant (antifreeze) in your
windshield washer.
It can damage your
washer system and paint.
5-38

Brake Fluid
Your brake master cylinder reservoir is filled with DOT-3
brake fluid. See
Engine Compantment Overview on
page
5-12 for the location of the reservoir.
There are only two reasons why the brake fluid level
in the reservoir might go down. The first is that the brake
fluid goes down to an acceptable level during normal
brake lining wear. When new linings are put in, the fluid
level goes back
up. The other reason is that fluid is
leaking out of the brake system.
If it is, you should have
your brake system fixed, since a leak means that
sooner or later your brakes won’t work well, or won’t
work at all.
So, it isn’t a good idea to “top off your brake fluid.
Adding brake fluid won’t correct a leak.
If you add fluid
when your linings are worn, then you’ll have too much
fluid when you get new brake linings. You should add (or
remove) brake fluid, as necessary, only when work is
done
on the brake hydraulic system.
If yo, ..rave 1,- _._____ rake ---id, it ~~-1 spill on
the engine. The fluid will burn if the engine is
hot enough. You or others could be burned,
and your vehicle could be damaged. Add brake
fluid only when work is done on the brake
hydraulic system. See “Checking Brake Fluid”
in this section.
Refer to the Maintenance Schedule to determine when
to check your brake fluid. See
Part C: Periodic
Maintenance Inspections on page 6-14.
5-39

Checking Brake Fluid
You can check the brake fluid without taking off the cap.
What to Add
When you do need brake fluid, use only DOT-3 brake
fluid.
Use new brake fluid from a sealed container
only. See
Part Dr Recommended Fluids and Lubricants
on
page 6- 16.
Just look at the brake fluid reservoir. The fluid level
should be above
MIN. If it isn’t have your brake system
checked to see
if there is a leak. Always
clean the brake fluid reservoir cap and the area
around the cap before removing it. This will help
keep dirt from entering the reservoir.
With the wrong kind
of fluid in your brake
system, your brakes may not work well, or they
may not even work at all. This could cause a
crash. Always use the proper brake fluid.
After work is done on the brake hydraulic system,
make sure the level is above the MIN but not over the
MAX mark.
5-40

Notice:
Using the wrong fluid can badly damage brake
system parts. For example, just a few drops of
mineral-based
oil, such as engine oil, in your
brake system can damage brake system
parts
so badly that they’ll have to be replaced.
Don’t let someone
put in the wrong kind of fluid.
If you spill brake fluid on your vehicle’s painted
surfaces, the paint finish can be damaged.
Be careful not to spill brake fluid on your
vehicle.
If you do, wash it off immediately.
See “Appearance Care” in the Index.
Brake Wear
Your vehicle has four-wheel disc brakes.
Disc brake pads have built-in wear indicators that make
a high-pitched warning sound when the brake pads
are worn and new pads are needed. The sound
may come and go or be heard all the time your vehicle
is moving (except when you are pushing on the
brake pedal firmly). The
brake wear warning sound means that soon
your brakes won’t work well. That could lead to
an accident. When you hear the brake wear
Notice: Continuing to drive with worn-out brake
pads could result
in costly brake repair.
Some driving conditions or climates may cause a brake
squeal when the brakes are first applied or lightly applied.
This does not mean something is wrong with your brakes.
Properly torqued wheel nuts are necessary to help
prevent brake pulsation. When tires are rotated, inspect
brake pads for wear and evenly tighten wheel nuts in
the proper sequence
to GM torque specifications.
Brake linings should always be replaced as complete
axle sets.
See
Brake System Inspection on page 6- 15
5-41

Brake Pedal Travel Battery
See your dealer if the brake pedal does not return to
normal height, or
if there is a rapid increase in
pedal travel. This could be a sign of brake trouble.
Brake Adjustment
Every time you make a brake stop, your disc brakes
adjust for wear.
Replacing Brake System Parts
The braking system on a vehicle is complex. Its many
parts have to be of top quality and work well together
if
the vehicle is to have really good braking. Your vehicle
was designed and tested with top-quality
GM brake parts.
When you replace parts of your braking system -for
example, when your brake linings wear down and you
need new ones put in
- be sure you get new approved
GM replacement parts. If you don’t, your brakes may no
longer work properly. For example, if someone puts in
brake linings that are wrong for your vehicle, the balance
between your front and rear brakes can change
- for the
worse. The braking performance you’ve come to expect
can change in many other ways
if someone puts in the
wrong replacement brake parts. Your new
vehicle comes with a maintenance free
ACDelco@ battery. When it’s time for a new battery, get
one that has the replacement number shown on the
original battery’s label. We recommend an ACDelco@
battery. See
Engine Compartment Overview on
page
5-12 for battery location.
Warning: Battery posts, terminals and related
accessories contain lead and lead compounds,
chemicals known to the State of California to cause
cancer and reproductive harm. Wash hands after
handling.
5-42

Vehicle Storage
If you’re not going to drive your vehicle for 25 days
or more, remove the black, negative
(-) cable from the
battery. This will help keep your battery from
runnir
-- down.
Batte
s have acid that ca )urn I and gas
that can explode. You can be badly hurt if you
aren’t careful. See “Jump Starting” next for
tips on working around a battery without getting hurt.
Contact your dealer
to learn how to prepare your
vehicle for longer storage periods.
Also, for your audio system, see Theft-Deterrent
Feature on page
3-8 1.
Jump Starting
If your battery (or batteries) has run down, you may
want
to use another vehicle and some jumper cables to
start your vehicle. Be sure to follow the steps below
to do it safely. Batteries can hurt you.
They can be dangerous
because:
They contain acid that can burn you.
0 They contain gas that can explode or
0 They contain enough electricity to ignite.
burn you.
If you don’t follow these steps exactly, some or
all of these things can
hurt you.
Notice: Ignoring these steps could result in costly
damage to your vehicle that wouldn’t be covered
by your warranty.
Trying to start your vehicle by pushing or
pulling it
won’t work, and it could damage your vehicle.
1. Check the other vehicle. It must have a 12-volt
battery with a negative ground system.
5-43